Optical and sedimentological properties of marine sediments, offshore Newfoundland
University of New Brunswick
Two cores from the IMAGES MD95-101 North Atlantic Cruise were utilized to evaluate the use of digital colour data to determine composition and texture, and sediment source or provenance. These cores are located beneath the iceberg and sea-ice pathways which transport sediment from Hudson Strait and the St. Lawrence Seaway to the North Atlantic Ocean Core 2024, to the northeast of Newfoundland on the flank of Orphan Knoll preserves a record of rapidly-deposited sedimentary layers, or Heinrich events, which are thought to reflect massive iceberg discharge from the Laurentide ice sheet. The second core, 2028, located southeast of Newfoundland on Fogo Seamount, records a signal of glacial discharge from the Gulf of St. Lawrence and contains Carboniferousredbed sediments derived from the Canadian Maritime Provinces. This study found that redness can be used as an indicator of glacial states: high redness corresponds to periods of glaciation, while low redness to inter-glacial periods. When plotted against visible wavelength, the first derivative of spectral reflectance curves show a characteristic peak at ~575 nm when hematite is present in the sediment matrix. Colour can be used to map the distribution of source beds and their subsequent transport by oceanic currents. The relationship between luminance and carbonate content provides a tool for making predictions on carbonate content. High luminance corresponds to high carbonate content. Luminance can also be used to indicate glacial state when plotted with oxygen isotopes. High luminance indicates a glacial state and low luminance an inter-glacial.